Avoid setting / depending on flags when transitioning, and when fields are known to be constant.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index fd4cc351af8b07d7fad9c547bfce99f04586b708..46e9b54ee08a9b2168ccf3ed3ae26c9ae581cba8 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -4483,8 +4483,8 @@ HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
 
   HStoreNamedField *instr;
   if (FLAG_track_double_fields && field_access.representation().IsDouble()) {
-    HObjectAccess heap_number_access =
-        field_access.WithRepresentation(Representation::Tagged());
+    HObjectAccess heap_number_access = field_access.WithRepresentation(
+        Representation::Tagged(), HObjectAccess::CONSTANT);
     if (transition_to_field) {
       // The store requires a mutable HeapNumber to be allocated.
       NoObservableSideEffectsScope no_side_effects(this);
@@ -5388,7 +5388,8 @@ HLoadNamedField* HGraphBuilder::BuildLoadNamedField(HValue* object,
   if (FLAG_track_double_fields && access.representation().IsDouble()) {
     // load the heap number
     HLoadNamedField* heap_number = Add<HLoadNamedField>(
-        object, access.WithRepresentation(Representation::Tagged()));
+        object, access.WithRepresentation(
+            Representation::Tagged(), HObjectAccess::CONSTANT));
     heap_number->set_type(HType::HeapNumber());
     // load the double value from it
     return New<HLoadNamedField>(